The present invention relates to aquatic alarms and sound systems and, more particularly to apparatus for producing high-fidelity sound underwater, and for reliably signalling unauthorized activity in or near a body of water such as a swimming pool or spa.
Traditionally, underwater speakers have been used primarily for public plunges and aquatic athletic events. They have been either temporary installations using pulley methods for lowering the speaker into the water, or permanent installations that project outwardly from the concrete side-walls of a swimming pool. In the latter case, in-field repair or replacement has been extremely difficult, if not impossible. Conventional underwater speakers have relatively poor fidelity in that they introduce unwanted distortion, and they have limited frequency response in that they typically can only reproduce high frequencies. Consequently, underwater speakers are not normally used for producing music. This poor performance is related to an alignment spider that is typically connected to a diaphragm of the speaker for preventing contact between an attached voice coil and a permanent magnet that is closely spaced thereto.
Intrusion alarms for swimming pools and the like are known. Typically they produce an alarm signal in response to wave motion that is generated when, for example, a child falls into the pool. Such alarms are often ineffective in that a child can enter the pool and drown without producing sufficient wave motions to trip the alarm, or the alarm is not triggered by the initial entry but only after the child is in distress--possibly too late for help to arrive in time. Also, existing alarm systems do not distinguish between normal recreational activity and situations requiring assistance or intervention. Moreover, wave motion sensors are subject to damage from normal recreational activity, and from weathering.
Thus there is a need for an underwater speaker system that is effective for producing High-fidelity sound, particularly at low frequencies, that is convenient to install, easy to service, and does not interfere with normal aquatic activities. There is a further need for a pool intrusion alarm that is effective for monitoring a body of water, signalling unauthorized entry, whether or not such activity is accompanied by significant wave activity, and that is not subject to damage from normal pool activity or weathering.